Optical waveguides consist of a transparent waveguiding core surrounded by transparent materials of lower indices of refraction. Several general methods are utilized for fabrication of optical waveguides.
Optical waveguides fabricated in GaAs/AlGaAs structures by laser-assisted etching has been reported in Integrated And Guided-Wave Optics, 1989 Technical Digest Series, 4, 64-67 (Optical Society of America).
U.S. Pat. No. 4,842,677 describes excimer laser etching of high resolution conductive patterns involving the use of an organic polymeric resist. Other publications relating to photoablation of organic polymers include J. Appl. Phys., 66(3), 1411 (1989).
Methods of fabricating organic waveguides are a newly evolving technology. A review article in Journal Of Lightwave Technology, 7(10), 1445 (1989) describes several polymeric channel waveguide fabrication routes, such as etching methods which include wet chemistry etching, reactive ion etching, excimer laser ablation, and the like.
New developments in organic waveguide technology involve the use of polymers with side chains that exhibit second order nonlinear optical susceptibility. Side chain polymers are described in U.S. Pat. Nos. 4,801,670; 4,804,255; 4,808,332; 4,882,865; and 4,865,406.
When a side chain polymer waveguiding thin film medium is subjected to an electric field to induce a noncentrosymmetric molecular orientation of the polymer side chains, the waveguiding medium exhibits second order nonlinear optical susceptibility .chi..sup.(2). The electrooptic activity of the side chain polymer waveguiding medium is proportional to the degree of noncentrosymmetric molecular orientation induced by electric field poling, which in turn is proportional to the strength of the applied electric field.
For wave interactions in a thin film waveguiding medium to be efficient, the velocities of the different electromagnetic waves must be matched. U.S. Pat. No. 4,865,406 describes a frequency doubling polymeric waveguide in which phase-matching of propagating light waves is achieved with a periodic second order nonlinear optically responsive waveguiding medium.
There is continuing interest in the development of new and improved techniques for the fabrication of organic optical waveguides which overcome some of the inherent deficiencies of optical waveguide formation in transparent organic media, and which provide waveguides exhibiting an improved wave interaction efficiency.
Accordingly, it is an object of this invention to provide a method for the production of noncentrosymmetric polymeric optical waveguides by electric field poling with a novel combination of electrodes.
It is a further object of this invention to provide side chain polymeric optical waveguides which have a two-dimensional channel waveguiding structure, and which have the polymer side chains poled bidirectionally to provide a noncentrosymmetric orientation of periodic reverse polarity for efficient phase-matching of propagating radiation waves.
Other objects and advantages of the present invention shall become apparent from the accompanying description and Examples.